As of 2000, 380,000 patients in the United States received dialysis for End Stage Renal Disease at a cost of $19.5 billion. Hemodialysis requires patient treatment 3 times a week for 3-4 hours. Peritoneal dialysis is an option utilized by less than 10% of patients requiring manual exchange of 2 liters of dialysate every 4 hours or having a machine make these exchanges more frequently while the patient is sleeping. Compliance is low for this intense procedure, and the treatment becomes inadequate with complete kidney failure, requiring a transfer to hemodialysis. Unfortunately, mortality with either technique is over 20% per year. Sonos Medical's ultimate goal is to produce a wearable, automated, peritoneal-based artificial kidney that operates continuously to remove metabolic wastes and toxins. This will liberate the dialysis patient from the chore of present therapy and eliminate the rapid biochemical swings and fluid shifts that cause a constellation of debilitating symptoms and impose a very restricted life style. The unit will consist of a disposable core sorbent assembly, combined with connectors, waste disposal for excess fluid, and enrichment reservoirs for additives. The Phase I SBIR project will test the efficiency and interoperability of the 4 modules that comprise the sorbent assembly. The Specific Aims are: 1) Immobilize urease to hydrolize urea, the major waste eliminated by the kidney, 2) Develop a cation exchange unit based on zirconium phosphate, 3) Achieve anion exchange using a zirconium oxide module, 4) Optimize removal of creatinine and other small to medium organics with an activated charcoal module, 5) Integrate these cartridges for 4 hours at 2L/hr of continuous removal of wastes from a model spent dialysate, and 6) Scale up the system for an 8-10 hour nocturnal cycle. The Phase I effort continues for 6 months and delivers a collection of chemical and physical processes, performing in concert, forming the basis of an integrated, self-contained device for daytime and nocturnal peritoneal dialysis which will be developed during Phase II.